linux-kernel - Re: [PATCH v6 02/12] drivers: base: cacheinfo: setup DT cache properties early

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Date:   Mon, 15 Jan 2018 08:07:43 -0800 (PST)
From:   Palmer Dabbelt <palmer@...ive.com>
To:     sudeep.holla@....com
CC:     jeremy.linton@....com, linux-acpi@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, hanjun.guo@...aro.org,
        lorenzo.pieralisi@....com, rjw@...ysocki.net,
        Will Deacon <will.deacon@....com>, catalin.marinas@....com,
        Greg KH <gregkh@...uxfoundation.org>, viresh.kumar@...aro.org,
        mark.rutland@....com, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, jhugo@...eaurora.org,
        wangxiongfeng2@...wei.com, Jonathan.Zhang@...ium.com,
        ahs3@...hat.com, Jayachandran.Nair@...ium.com,
        austinwc@...eaurora.org, lenb@...nel.org, vkilari@...eaurora.org,
        morten.rasmussen@....com, albert@...ive.com, sudeep.holla@....com
Subject:     Re: [PATCH v6 02/12] drivers: base: cacheinfo: setup DT cache properties early

On Mon, 15 Jan 2018 04:33:38 PST (-0800), sudeep.holla@....com wrote:
> On Fri, Jan 12, 2018 at 06:59:10PM -0600, Jeremy Linton wrote:
>> The original intent in cacheinfo was that an architecture
>> specific populate_cache_leaves() would probe the hardware
>> and then cache_shared_cpu_map_setup() and
>> cache_override_properties() would provide firmware help to
>> extend/expand upon what was probed. Arm64 was really
>> the only architecture that was working this way, and
>> with the removal of most of the hardware probing logic it
>> became clear that it was possible to simplify the logic a bit.
>>
>> This patch combines the walk of the DT nodes with the
>> code updating the cache size/line_size and nr_sets.
>> cache_override_properties() (which was DT specific) is
>> then removed. The result is that cacheinfo.of_node is
>> no longer used as a temporary place to hold DT references
>> for future calls that update cache properties. That change
>> helps to clarify its one remaining use (matching
>> cacheinfo nodes that represent shared caches) which
>> will be used by the ACPI/PPTT code in the following patches.
>>
>> Cc: Palmer Dabbelt <palmer@...ive.com>
>> Cc: Albert Ou <albert@...ive.com>
>> Signed-off-by: Jeremy Linton <jeremy.linton@....com>
>> ---
>>  arch/riscv/kernel/cacheinfo.c |  1 +
>>  drivers/base/cacheinfo.c      | 65 +++++++++++++++++++------------------------
>>  include/linux/cacheinfo.h     |  1 +
>>  3 files changed, 31 insertions(+), 36 deletions(-)
>>
>> diff --git a/arch/riscv/kernel/cacheinfo.c b/arch/riscv/kernel/cacheinfo.c
>> index 10ed2749e246..6f4500233cf8 100644
>> --- a/arch/riscv/kernel/cacheinfo.c
>> +++ b/arch/riscv/kernel/cacheinfo.c
>> @@ -30,6 +30,7 @@ static void ci_leaf_init(struct cacheinfo *this_leaf,
>>  		CACHE_WRITE_BACK
>>  		| CACHE_READ_ALLOCATE
>>  		| CACHE_WRITE_ALLOCATE;
>> +	cache_of_set_props(this_leaf, node);
>
> This may be necessary but can it be done as later patch ? So far nothing
> is added that may break riscv IIUC.
>
> Palmer, Albert,
>
> Can you confirm ? Also, as I see we can thin down arch specific
> implementation on riscv if it's just using DT like ARM64. Sorry if
> I am missing to see something, so thought of checking.
>
> [...]

Sorry, I guess I'm a bit confused as to what's going on here.  RISC-V uses 
device tree on all Linux systems.

>> diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h
>> index 3d9805297cda..d35299a590a4 100644
>> --- a/include/linux/cacheinfo.h
>> +++ b/include/linux/cacheinfo.h
>> @@ -99,6 +99,7 @@ int func(unsigned int cpu)					\
>>  struct cpu_cacheinfo *get_cpu_cacheinfo(unsigned int cpu);
>>  int init_cache_level(unsigned int cpu);
>>  int populate_cache_leaves(unsigned int cpu);
>> +void cache_of_set_props(struct cacheinfo *this_leaf, struct device_node *np);
>>
>
> IIUC riscv is the only user for this outside of cacheinfo.c, right ?
> Hopefully we can get rid of it.
>
> Other than that, it looks OK. I will wait for response from riscv team
> do that these riscv related changes can be dropped or move to later
> patch if really needed.